1. Field of the Invention
The present invention is related to a heating apparatus and a method of heating objects inside an oven using microwaves in order to carry out drying, warming, thawing, cooking, roasting, sterilizing, concentrating and the like.
2. Description of the Prior Art
In the case were objects are heated using microwaves, when microwaves emitted from a magnetron are passed through a waveguide and introduced inside a tank, a portion of such introduced microwaves form reflected waves which travel in the opposite direction and return to the magnetron, thereby creating an energy loss and damaging the magnetron due to the heat generated by such reflected microwaves. Prior art technology for preventing this includes mounting a matching device midway in the waveguide to match the microwaves in order to reduce reflected waves, and mounting an isolator near the microwave generator to absorb and eliminate reflected waves.
Further, a stirrer is generally mounted inside the oven to disperse the microwaves in order to achieve matching.
Further, in the case where a plurality of microwave introduction ports are provided in the oven, these microwave introduction ports are arranged away from mutually opposing positions to prevent increased reflected waves and mutual interference of the microwaves introduced through such introduction ports, and in the case of rectangular microwave introduction ports, if a horizontal arrangement is used on one side, a vertical arrangement can be used on the opposite side away from opposing positions.
However, the isolator and matching device used in the prior art are extremely expensive and form the main cause of high costs introduced when the microwave generator is to be used a lot for industrial applications, and for this reason the use of such high value-added energy microwaves has been limited.
Further, a stirrer is generally provided to disperse the microwaves inside the oven in order to achieve uniform heating, but because this requires a significant mounting space for holding the rotation axle for the rotor and the motor required for the stirrer, it is impossible to provide a large number of microwave introduction ports, and this makes it difficult to achieve uniform heating by means of a plurality of microwave introduction ports. Further, because the incident waves interfere with each other and become dispersed while the stirrer is rotating, a fluctuating increase and decrease in reflected waves normally appears, and this has made it difficult to achieve a stable reduction in reflected waves.
Further, in the case where a plurality of microwave introduction ports are provided in the oven, when these microwave introduction ports are arranged at positions away from opposing positions, minute changes in position can have subtle adverse effects on uniform heating and matching, and this has created problems for heating matching and made it impossible to achieve a sufficient reduction in reflected waves. In particular, this problem is striking in the case where the object being heated is fixed in place.